Button-type batteries are small thin energy cells that are commonly used in watches and other electronic devices requiring a thin profile. FIGS. 1 and 2 show a conventional button-type battery 20. Battery 20 includes an anode 22, a cathode 24, a porous separator 26 separating the anode and cathode, and an electrolyte 28 which facilitates ion conductivity between the anode and cathode.
These internal battery components are housed within a metal casing formed by a lower conductive can 30 and an upper conductive lid 32. Can 30 electrically contacts cathode 24 and thereby forms the positive battery terminal. Lid 32 electrically contacts anode 22 to form the negative battery terminal. The can and lid are crimped or pressed together to form a fluid-tight seal 34 which entirely encloses the anode, cathode, separator, and electrolyte. An insulating gasket 36 is provided within primary seal 34 between lid 32 and can 30 to electrically insulate the two housing members.
There is a need in button-type battery usage to make such energy cells thinner. Today, the thinnest commercially available button-type battery has a thickness of 1.2 mm (47.2 mils). It would be desirable to make a thinner battery, particularly one having a thickness of less than 1 mm (39.4 mils). A countering concern, however, is that the integrity of the fluid-tight seal cannot be compromised simply to achieve the goal of thinner batteries.
Accordingly, it is desirable to design a button-type battery with a very thin profile, yet without degrading the integrity of the fluid-tight seal.